The present invention relates to a method of hydrogenating heavy-oil. More precisely, it relates to a method of hydrogenating heavy oil with a catalyst partly comprising a regenerated catalyst, concretely, to a method of denitrifying and desulfurizing heavy oil with such a catalyst.
For petroleum purification, there are many methods of purifying different fractions through hydrogenation. They include desulfurization and denitrification of naphtha, kerosene, light oil, etc.; desulfurization, denitrification and cracking of heavy-gravity light oil; and desulfurization and denitrification of residual oil and heavy oil. Of those, the catalysts used for hydrogenating naphtha, kerosene and light oil all having a relatively low boiling point and containing few metal impurities such as vanadium and others are degraded only a little.
The catalysts used for hydrogenating them will be degraded almost exclusively by a small amount of carbonaceous material deposited thereon. Therefore, the used catalysts could be regenerated and reused if the carbonaceous deposit is removed from them, for example, by firing the deposit. Removing the carbonaceous deposit to regenerate the used catalysts into reusable ones does not require any severe fire control, as the amount of the deposit is small. Even when once used, some used catalysts will be degraded only a little and could be directly reused as they are. Therefore, the catalysts of that type could be used repeatedly for treating naphtha, kerosene, light oil and the like, not requiring any specific care.
Recently, hydrogenation catalysts for heavy-gravity light oil and reduced-pressure light oil have been reused through regeneration or the like, and some methods for regenerating and reusing them have been established. For example, it is known that, in the hydro-cracking process for heavy-gravity light oil, both the hydro-cracking catalyst and the hydro-denitrification catalyst for the pretreatment can be regenerated and reused through hydrogen activation or oxygen activation.
On the catalysts used for hydrogenation of these petroleum distillates, few oil-derived metals such as vanadium and the like deposit, since the distillates contain few metal impurities. In addition, the amount of the carbonaceous material that may deposit on the used catalysts is small and the carbonaceous deposit could be readily fired away. While the catalysts with the carbonaceous deposit thereon are regenerated by firing them, their surfaces will not be heated up to so high temperatures, and the pore structure of the fired catalysts and even the condition thereof to carry the active metal phase therein will change little. Therefore, the regenerated catalysts could be reused with no difficulty for treating petroleum distillates such as heavy-gravity light oil, reduced-pressure light oil and others (Studies in Surface and Catalysis, Vol. 88, p. 199, 1994).
However, in hydrogenation of residual oil having a higher boiling point or of heavy oil containing undistillable fractions, a large amount of metallic material and carbonaceous material deposits on the used catalysts, since the oil to be processed contains a large amount of metal impurities and easily-carbonizing substances such as asphaltene, etc. In addition, from the viewpoint of their quality, the used catalysts having both the metallic deposit and the carbonaceous deposit thereon could not be easily regenerated to remove the deposits therefrom by firing them (Catal. Today, Vol. 17, No. 4, p. 539, 1993; Catal. Rev. Sci. Eng., 33 (3 and 4), p. 281, 1991). For these reasons, the used catalyst have heretofore been discarded without being recycled.
The present invention is to regenerate the catalysts used and deactivated through hydrogenation of heavy oil and others, which have heretofore been discarded without being recycled, and its object is to provide a method of effectively using the regenerated catalysts for hydrogenation of heavy oil.
We, the present inventors have assiduously studied, and, as a result, have found that, when a catalyst having been deactivated through hydrogenation of heavy oil and others is regenerated and when the combination of the regenerated catalyst and a fresh catalyst is optimized, then the combined catalyst system is still effective for hydrogenation of heavy oil. In addition, we have further found that, when the deactivated catalyst is regenerated in such a manner that the amount of the impurities still adhering to the regenerated catalyst and the physical properties of the regenerated catalyst are controlled to fall within a specifically defined range, then the thus-regenerated catalyst is especially effective for hydrogenation of heavy oil. On the basis of these findings, we have completed the present invention.
Specifically, the summary of the invention is as follows:
(1) A method of hydrogenating heavy oil, which is characterized by passing heavy oil through at least a layer of a regenerated catalyst or a layer containing a regenerated catalyst.
(2) A method of hydro-denitrifying heavy oil in a reaction zone filled with a catalyst, which is characterized by catalyst disposition of such that a regenerated catalyst is disposed in the former stage of at least a part of the reaction zone and a fresh catalyst is disposed in the latter stage thereof.
(3) The hydro-denitrifying method of above (2), wherein the amount of the fresh catalyst filled in at least a part of the reaction zone falls between 20 and 95% by volume and that of the regenerated catalyst filled therein falls between 5 and 80% by volume.
(4) A method of hydro-desulfurizing heavy oil in a reaction zone filled with a catalyst, which is characterized by catalyst disposition of such that a fresh catalyst is disposed in the former stage of at least a part of the reaction zone and a regenerated catalyst is disposed in the latter stage thereof.
(5) The hydro-desulfurizing method of above (4), wherein the amount of the regenerated catalyst filled in at least a part of the reaction zone falls between 5 and 80% by volume and that of the fresh catalyst filled therein falls between 20 and 95% by volume.
(6) A method of hydrogenating heavy oil, for which is used a reaction zone comprising at least three reaction layers of regenerated catalyst layers and fresh catalyst layers disposed alternately.
(7) The method of hydrogenating heavy oil of above (6), wherein the liquid hourly space velocity (LHSV) of the heavy oil passing through the regenerated catalyst layer to be hydrogenated therethrough is larger than 1 hrxe2x88x921.
(8) A method of hydrogenating heavy oil, for which is used a reaction zone comprising a regenerated catalyst and a fresh catalyst and having at least a mixed layer of the two.
(9) The method of hydrogenating heavy oil of any one of above (6) to (8), wherein the amount of the regenerated catalyst filled in the reaction zone falls between 5 and 80% by volume and that of the fresh catalyst filled therein falls between 20 and 95% by volume.
(10) The method of hydrogenating heavy oil of any one of above (1) to (9), wherein the vanadium content of the regenerated catalyst is at most 35% by weight.
(11) The method of hydrogenating heavy oil of any one of above (1) to (10), wherein the carbon content of the regenerated catalyst is at most 15% by weight.
(12) The method of hydrogenating heavy oil of any one of above (1) to (11), wherein the specific surface area of the regenerated catalyst falls between 60 and 200 m2/g.
(13) The method of hydrogenating heavy oil of any one of above (1) to (12), wherein the pore volume of the regenerated catalyst falls between 0.3 and 1.0 cc/g.
(14) The method of hydrogenating heavy oil of any one of above (1) to (13), wherein the regenerated catalyst is from a used catalyst having at least one metal of molybdenum, tungsten, cobalt and nickel carried on an oxide carrier, the catalyst having been used for hydrogenating mineral oil and then regenerated.
(15) The method of hydrogenating heavy oil of above (14), wherein the oxide carrier is alumina, and the metal carried on it is nickel and molybdenum.
(16) The method of hydrogenating heavy oil of above (14), wherein the oxide carrier is alumina containing at least one oxide of phosphorus, boron or silicon, and the metal carried on it is nickel or cobalt, and molybdenum.
(17) The method of hydrogenating heavy oil of any one of above (14) to (16), wherein the nickel or cobalt content of the catalyst having the metal carried on its carrier falls between 0.1 and 10% by weight and the molybdenum content thereof falls between 0.1 and 25% by weight.
(18) The method of hydrogenating heavy oil of any one of above (10) to (17), which is for hydro-denitrifying heavy oil.
(19) The method of hydrogenating heavy oil of any one of above (10) to (17), which is for hydro-desulfurizing heavy oil.